Frankia KB5 possesses a hydrogenase immunologically related to membrane-bound [NiFe]-hydrogenases

The immunological relationship of the hydrogenase in Frankia KB5 to hydroge nases in other microorganisms was investigated using antisera raised agains t holo-[NiFe]-hydrogenases isolated from Alcaligenes latus, Azotobacter vin elandii, Ralstonia eutropha, and the small and large hydrogenase subunits f rom Bradyrhizobium japonicum. The antisera raised against the A. latus, R. eutropha, and B. japonicum (large subunit) polypeptides were found to recog nize two polypeptides, corresponding to the unprocessed and processed forms of the hydrogenase subunit in Frankia KB5. None of the antisera, including the antibodies produced against the small hydrogenase subunit isolated fro m B. japonicum, recognized any polypeptide related to the small hydrogenase subunit in Frankia KB5. An immunogold localization study of the intracellu lar distribution of hydrogenase in Frankia KB5, with the cryo-section techn ique, showed that labeling in the membrane of both hyphae and vesicles was positively correlated with hydrogenase activity.